The enzyme content of expressed prostatic fluid will be determined in three groups of men; namely, 1) Men subjected to prostatic biopsy or prostatectomy; 2) Patients with a clinical diagnosis of benign prostatic hyperplasia, prostatitis, or normal prostate; and 3) Asymptomatic men 50 years of age and over who are being subjected to yearly health status screening studies. Initially, microscopic evaluation of cell content of prostatic fluid will be followed by determinatton of lactic dehydrogenase (LDH) isozyme content. Clinical and histologic findings will be correlated with the results of these analyses to evaluate the possibility that an abnormal LDHV/LDHI ratio in expressed prostatic fluid may be associated with early prostatic malignancy and may precede its histologic recognition. Determination of other enzymes including leucine aminopeptidase and glucose-6-phosphate dehydrogenase will be carried out to assess their value in identification of prostatic pathology. Serial studies of prostatic fluid and correlation with clinical and histologic diagnosis is planned for the study groups.